[ranger] validate the JAR file path of the subprocess
[ranger] validate the JAR file path of the subprocess

This patch updates the previous flag validator for --ranger_java_path
to be group validation for all Ranger-related flags including the JAR
file path of the subprocess flag --ranger_jar_path.

Change-Id: I361689971dcd8dd74c13b90b61b922e7f7c7a88d
Reviewed-on: http://gerrit.cloudera.org:8080/15435
Reviewed-by: Adar Dembo <866ca730bfc7f544e3ebce604ceeba4879f23df0@cloudera.com>
Tested-by: Hao Hao <99da4db57fde39d3df9f1908299d10b8082bf864@cloudera.com>

helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu